Abstract

Genetic similarity owing to kin relationship is often invoked to explain the evolution of social cooperation. In this study, male color morphs of side-blotched lizards settle nonrandomly with respect to genetic similarity. Blue morphs tend to settle in close proximity to other blue morphs with high genetic similarity. Blue neighbors have three times the average fitness of blue males lacking such neighbors. Conversely, genetically similar males depress fitness of the orange morph. Moreover, orange males are hyperdispersed with respect to genetic similarity. Pedigree and dispersal data show that genetically similar blue neighbors are not kin. Instead, conditions for the evolution of dispersal and cooperation are promoted by an emergent property of the morph locus that increases genetic similarity within morphs: genome-wide correlational selection links many traits to the morph locus, including settlement behavior.